A combination of antibiotics taken for six months may help some people beat reactive arthritis, which is triggered by an infection, according to the results of a new study.

If confirmed by future research, it would be a major step forward to finding a cure for chronic forms of reactive arthritis, which most commonly follows the sexually transmitted disease chlamydia but can also be associated with infections caused by tainted food.

“We’ve traditionally just treated [these patients] with medications like methotrexate, so it’s just been treated like any other chronic inflammatory arthritis,” says lead researcher J. D. Carter, MD, who is Chief of Rheumatology at the University of South Florida College of Medicine in Tampa.

“This is the first study that says you can get to the source of the chlamydia and eradicate the chlamydia, the source of inflammation.”

Reactive arthritis, also called Reiter’s syndrome or seronegative spondyloarthropathy, typically develops within a month of an infection and is characterized by pain and swelling in no more than four joints – usually in the knees, ankles and feet; heel pain; conjunctivitis, or pink eye; pain and stiffness in the lower back; and skin problems including psoriasis or eczema.

Experts estimate that as many as 4 percent of the 3 million people infected with Chlamydia trachomatis bacteria each year may go on to develop reactive arthritis.

Symptoms typically last for three months to a year, but researchers say some data indicates 30 to 50 percent of patients develop a form of the disease that can linger for years.

Dr. Carter and his team tested two different combinations of antibiotics against a placebo in 42 patients with chronic forms of reactive arthritis. 

After six months of treatment, 63 percent of participants treated with antibiotics saw at least a 20 percent improvement in their symptoms compared with just 20 percent of the group that got the placebo.  

What’s more, 22 percent of people treated with antibiotics had a complete resolution of their symptoms while none in the placebo group saw their disease go away.

“We found that the patients randomized to combination antibiotics not only clinically improved but their infection was more likely to clear,” Dr. Carter says.

The study was published in the May 2010 issue of Arthritis & Rheumatism.

Researchers had previously tried to use antibiotics to treat reactive arthritis, with no effect.